Comparative Morphology of Chordates 



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Fig. 597. Eohippus, the - '<Ih\\ii horse" of the Lower Eocene, probably close 

 to the stem of the perissodactyls; length about 18 inches. (After Cope and Wood- 

 ward. Courtesy, Romer: "Vertebrate Paleontology," University of Chicago Press.) 



Fig. 598. Feet of horses. (Left) Manns. (Right) Pes. (A) Eohippus, a primitive 

 Lower Eocene perissodactyl with four toes in front and three behind. (B) Mio- 

 hippus, an Oligocene three-toed horse. (C) Merychippus, a late Miocene form with 

 reduced lateral toes. (D) Equus. (A, after Cope; B, C, after Osborn. Courtesy. 

 Romer: "Vertebrate Paleontology," University of Chicago Press.) 



